1. Field of the Invention
The invention relates generally to a gasification process for the production of producer gas and to a production device, system, and method for implementing the process and for the production of producer gas.
2. Background Art
A gasification process is generally a process by which solid or liquid material is converted into a gaseous form, a gaseous chemical composition formed of several other ingredients, or a gaseous mixture of several substances. The terms gasification and gasifier are often used to refer to a process and a device, respectively, for making producer gas from solid coal, coke, or other carbon source materials. Prior to gasification, source materials are often subjected to volatilization or heating to drive off volatiles such as methane (CH4). Sometimes the preheating is in the form of pyrolysis where biomass or coal turns into char releasing polycyclic aromatic hydrocarbons, tar and methane. A gasifier may be fed with the pyrolysed char. Producer gas is generally considered to be the gas produced by gasification of the carbon source after the volatiles such as methane and other aromatic hydrocarbons have been largely driven off by a heating or consumed by oxidation for producing heat for gasification of the carbon fuel source material.
Producer gas is generally a low grade fuel gas consisting chiefly of a combustible mixture of carbon monoxide, nitrogen and hydrogen. Producer gas may be generated by passing air together with steam over a carbon source such as coke or coal that is burning in a furnace or a generator. The producer gas is the product of thermal gasification of the carbon containing materials, in a gasifier or in a producer gas generator. Producer gas results from a high temperature reaction (>700° C.), where carbon reacts with steam (H20) or a limited amount of air or oxygen producing carbon monoxide (CO), molecular hydrogen (H2), and carbon dioxide (CO2). Typically the fuel is introduced through the top of the generator and air is forced upward through the burning carbon fuel such as coke or coal. The carbon of the fuel is oxidized by the portion of the oxygen of the air introduce from below to form the carbon monoxide. The nitrogen portion of the air, being inert, passes through the burning carbon fuel or fire generally without change. Steam is also introduced with the air so that hydrogen is also produced and the final gaseous product contains carbon monoxide, nitrogen and hydrogen.